Improved combination of cutters for threading wood-screws



T. J. SLOA N.

Threading Wood Screws.

Patented July 6, 1852.

u. PETERS. FhukmLilhagnpher' To all whom it may concern:

UNITED STATES PATENT OFFICE.

THOMAS J. SLOAN, or NEw YoRK, N. Y.

IMPROVED COMBINATION OF CUTTERS FOR THREADING WOOD-SCREWS, 8L0.

Be it known that I, THOMAS J SLoAN, of New York, N. Y., have invented a certain new and useful Improvement in the Machine for Threading Wood-Screws; and I do hereby declare'that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, making part hereof, in which Figure 1 is a plan; Fig. 2, an elevation; and

I Figs. 3 and 4, cross vertical sections taken at the lines A a and B b of Fig. 1.

The same letters indicate like parts in all the figures.

- It has long been essayed to thread woodscrews by means of burr-cutters, but I believe without success, as the threads thus out are left in a rough and unfinished state.

The object of my invention is to combine the advantages of rapid and easy cutting due to the use of the burr-cutter with the regular and highly-finished thread due to the use of the chaser when cutting at a slow motion; and to this end- The nature of my invention consists in combining the operation of forming the threads of wood-screws by means of the burr-cutter with the operation of finishing and smoothing the thread by means of a chaser, the screwblanks being in succession shifted from the operation of the burr-cutter, where the thread is cut and formed, to the chaser, where it is finished, thus combining the advantages of both systems.

In the accompanying drawings, a represents the frame, which may be modified to suit the judgment of the constructor, and b a shaft mounted on standards 0 c of the frame. This shaft carries two sets of arms d d cl d, in which turn two mandrels e 6, similar to those generally employed in machines for threading wood-screws. They are to be provided, in manner well known to persons conversant with this branch of the arts, with grippingjaws and their appendages for gripping the blanks and liberating them when threaded.

At their rear ends thetwo mandrels are geared together by means of cog-wheels f f, sothat any motion communicated to one shall cause the two to rotate together with equal velocity and I in opposite directions; and in addition to all this each mandrel carries a screw-leader g-as it is termed-to give the threading motion to the cutters for the purpose of giving the required pitch to the thread of the screws.

Just back of one of the mandrels and in a line with its axis there is an arbor h, which runs in boxes in the standards it of the frame in such manner as-to rotate and move therein longitudinally. This arbor receives the driving motion from some first mover by a belt or other appropriate means, and it carries a pinion j, which engages a cog-wheel k on a cam-shaft Z, and within the standards it there is another pinion m that turns freely on the said arbor, and between the inner end of this pinion and a collar n, attached to this arbor, there is a helical spring 0 interposed, the tension of which keeps the pinion against the outer standard and tends constantly to force the arbor inward. When this arbor is moved longitudinally outward, it clutches the pinion m by a clutch-pin p on the arbor striking against the clutch-pin g on the pinion, and in this condition motion is communicated by the pinion m to a cog-wheelr on the rear end of the shaft b, to which the said shaft is turned, causing the two mandrels to move about the axis of this shaft half a revolution, at the end of which motion the arms (I d are locked by a lock-lever s, operated by a cam 15 on the cam-shaft Z, the form of this cam being such as to permit the arms to be unlocked by the tension of a spring won the lever at the time the pinion m is clutched, and to force in the lever to lock the arms the moment the pinion is unclutched. tudinal motion of the arbor to clutch and unclutch the pinionm is .given by a cam 11 on the face of the cog-wheel 70 on the cam-shaft l, which makes one revolution for each complete operation of the machine. This cam acts on. one end of a lever w, the other end of which is forked to embrace the arbor h, and

bears against the inner face of the pinion j,

so that the action of this lever, by the cam 12, forces out the arbor to clutch the pinion, and after the cam has passed the lever permits the arbor to be forced back by the tension of the helical spring to unclutch the pinion m.

The longi- From the above it will be seen that frbifl,

the arbor h motions are communicated to the cam-shaft to operate the clutching and unclutching lever, to the lever for unlocking and locking the arms 01 d that carry the mandrels, to the shaft 1) for shifting, the mandrels, and, finally, to the wheels f f to give the rotating threading motion to the mandrels that carry the blanks, and thatas the arbor is moved to unclutch. the pinion m after the mandrels have been shifted, it'

immediately and at the end of the said: n10- tion-clutches one of the wheels onthe mandrels toimpart the rotary motion to, the man,- drels. A fresh blank havingtbeen fed in and gripped bythe jaws on that one of the. man;- drels not in line with'thearber h, the opera.- tion of the machine begins. The mandrels rotate, and as they rotate the back-restsa. a are forced up to their appropriate places by a cam 12 on the cam-shaft, whichcam actson the end of an arm 0 of a. rocker d, which rocker has a toepiece d, which strikes against the-back of one rest to forceand'keep it up, and. the said rocker carries an arm 6", connected by a joint-linlcfwith a like arm on another rocker d which acts in like man-- other end of which carries a pulley h to receive aband from some first mover to give the required velocity to the said burr. The

spindle of the said burr runs in the upper end of an: arm z'"on a sliding I'OCkrShflfll j, so that the burr-cutter can be moved toward and from the axis of the screw-blank by the rocking motion, and from end to end of theshank of the screw-blank by the sliding motion. A

spring lois employed to draw the rocker with theburr'cutter from the mandrel, and it 'is moved slowly from the point toward the head ofthe blank to give the pitch of the thread by means of a comb Z When engaged with the threads of the leader on the mandrel. This comb is on the end of an. arm 7%, attached to a sleeve-rocker n, that turns freely on the rocker and confined thereon endwise between shoulders. The said sleeve-rocker has two other arms 0 and 19, one attached to aspring q, the tension of which tends constantly to keep the comb in contact with the leader, and

the other to bear upon the periphery of a cam r on the cam-shaft, so formed that at the end of each cut the comb is lifted out of the thread of the leader to permit the tension of the spring 70 to draw the rocker with the burr-cutter and comb forward for the repeti tion of the operation, and then the cam permits the tension of the spring to re-engage the comb with the threads of the'leader. The can1 has two such projections on its periphery, as two cuts will be sufficient to cut the thread so far as it is to be cut by the burr; 'but it will be obvious that the number may be varied at pleasure. As the burr-cutter ro tates with great velocity, the mandrel carrying the blank may rotate slowly,tand as the burr begins-to cut at the point it removes all the surplus metal from the blank with facility and without. strainingthemetal' otthe shank of the blank; and thereforepoint'ed screws can be readily made'without previously milling the blank. The motion oftheburr' toward and from the axis of the blank for thQSIIG- cessive cuts and, for the running back tore.- peat the cuts is givenzby a mold sf, against the face of which runs a part of the rocker that carries the burr. The mechanism for giving the required motions tothis mold 'isnot represented, nor is it deemed necessary to describe it, as it is well known to=persons-conversant with machinery for threading;woodscrews. 1

Instead of the mol'chvany other adequate means may be employed for guiding-the-burrcutter toward and from the axis of theblank. So soon as a blank has thus been'operated up to form a thread by the burr the' mandrels are shifted,.as before describethwhichbrings-the other mandrel to the position above described to receive a fresh: blank and have athread out upon it by means of the burr-cuttenand at the same timethe blank previously-acted upon is brought to the other position to have the thread smoothed and finished by a chaser t mounted on. atool-post u, projecting from: a sliding rock-shaft 1;", provided with a comb-w and other appendages, just likethe-oneabove described, and operated in like manner, except that on thisside-the chaser for chasing or fins ishing. the thread moves f rom 'the head toward the point, of the screw.

From the foregoing it will be seen that the rough cutting-that is,: removi-ng the mass of the material to form the'thread on the blanks-is efiected by the burr-cutter, which has anindependent cutting mot-ion, which may be carried to a high velocity without any injurious effect,zwhile themandrel which carriesthe blank can be turned with acomparatively slow motion toavoid all theinj urious consequences of a rapid motionand insure a high finish under the operation. of the chaser.

I do not wish to limit myself to the mode of construction of the various parts or their arrangement, as these may be varied to a great extent without changing the principle or mode of operation of my invention.

What I claim as my invention, and desire to secure by Letters Patent, is

The method,' substantially as herein specified, of cutting away the mass of the metal to form the thread by means of a burr-cutter, in

combination with the method, substantially as specified, of finishing and smoothing the thread by means of the chaser, as set forth.

. THOS. J. SLOAN. Witnesses:

WM. H. BISHOP, CHARLES N. BARNBURGH. 

